Determination of the Mobile-Hydrogen Charge State in Hydrogenated Amorphous Silicon

Brent P. Nelson, Yueqin Xu, Robert C. Reedy, Richard S. Crandall, A. Harv Mahan, Howard M. Branz

Research output: Contribution to conferencePaperpeer-review

2 Scopus Citations


We find that hydrogen diffuses as H+, H0, or H- in hydrogenated amorphous silicon depending on its location within the i-layer of a p-i-n device. We annealed a set of five p-i-n devices, each with a thin deuterium-doped layer at a different location in the i-layer, and observed the D-diffusion using secondary ion mass spectrometry (SIMS). When H-diffuses in a charged state, electric fields in the device strongly influence the direction and distance of diffusion. When D is incorporated into a device near the p-layer, almost all of the D-diffusion occurs as D+, and when the D is incorporated near the n-layer, most of the D-diffusion occurs as D-. We correlate the preferential direction of D-motion at given depth within the i-layer, with the local Fermi level (as calculated by solar cell simulations), to empirically determine an effective correlation energy for mobile-H electronic transitions of 0.39 ± 0.1 eV. Using this procedure, the best fit to the data produces a disorder broadening of the transition levels of ∼0.25 eV. The midpoint between the H0/+ and the H0/- transition levels is ∼0.20 ± 0.05 eV above midgap.

Original languageAmerican English
StatePublished - 2001
EventAmorphous and Heterogeneous Silicon Based Films 2001 - San Francisco, CA, United States
Duration: 16 Apr 200120 Apr 2001


ConferenceAmorphous and Heterogeneous Silicon Based Films 2001
Country/TerritoryUnited States
CitySan Francisco, CA

NREL Publication Number

  • NREL/CP-520-32936


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